Currently available semiconductor substrate cleaning equipment suffers from high cost per unit substrate cleaned, unreliable removal of large flat particles, and of particles located along the beveled edge of a semiconductor substrate, lack of scalability and inability to easily adapt to various processing sequences, or to changes (e.g., increases) in semiconductor substrate size. Among the many factors that contribute to substrate cleaning costs, the capital cost of substrate handlers which move semiconductor substrates between various locations presents a significant expense. Another significant expense arises because semiconductor substrate cleaning processes are performed within a clean room environment. The larger the area occupied by the cleaning system (i.e., the larger the footprint) the more expensive the cleaning system is to operate, due to the high cost of clean room area.
Unreliable cleaning, however, increases cleaning costs more than any other factor. As semiconductor substrates increase in size, failures become more expensive, and as devices formed on semiconductor substrates decrease in size, particles are more likely to cause failures.
Accordingly, improvements are needed in the field of semiconductor substrate cleaning.
An inventive semiconductor substrate cleaning system comprises a plurality of cleaning modules, each module has a substrate support for supporting a vertically oriented semiconductor substrate during a cleaning process, and each module is positioned such that the substrate supports thereof are spaced a fixed distance X. An input module positioned adjacent a first end module of the plurality of cleaning modules has a substrate support positioned a distance X from the substrate support of the first end module, and an output module positioned adjacent a second end module of the plurality of cleaning modules has a substrate support positioned the distance X from the substrate support of the second end module. A semiconductor substrate transfer mechanism having a plurality of substrate handlers spaced the distance X is movably coupled above the plurality of cleaning modules and above the input and output modules so as to move forward and backward the distance X, thereby simultaneously carrying semiconductor substrates between adjacent ones of the input module, the cleaning modules and the output module.
For cases where the substrates are not loaded vertically into the input module and/or are not unloaded vertically from the output module, the input and/or output modules may respectively include a mechanism for receiving a semiconductor substrate in a horizontal orientation and for rotating the semiconductor substrate to a vertical orientation and a mechanism for receiving a semiconductor substrate in a vertical orientation and for rotating the semiconductor substrate to a horizontal orientation. Likewise, to facilitate wafer handling, the input module may orient the substrate to place the substrate""s flat in a known position (i.e., flat finding) such that the wafer handler will not contact the flat. In steady state operation, semiconductor substrates may be loaded to and unloaded from the system, are appropriately oriented horizontally or vertically and/or have their flats appropriately positioned while other substrates are being cleaned. System productivity therefore may be enhanced as the system need not idle during the time required for substrate load/unload and orient operations.
After semiconductor substrates are loaded to and unloaded from the system via the input module and the output module, the overhead transfer mechanism lowers the wafer handlers. In one aspect the wafer handlers are simultaneously lowered into the input module and the various cleaning modules to pick up or xe2x80x9cgripxe2x80x9d semiconductor substrates contained therein. Thereafter, by simply raising, indexing forward the distance X and lowering, the transfer mechanism simultaneously transfers a plurality of single substrate batches from one module to the next. The transfer mechanism ungrips the substrates, raises and returns to the home position while substrates are loaded/unloaded and oriented in the input and output modules. This process repeats until each substrate receives the desired processing and is unloaded. In this aspect, the simplicity of the simultaneous substrate transfer mechanism provides accurate yet cost effective substrate transfer.
The entirely vertical orientation of the cleaning modules requires minimal footprint, and enables the inventive cleaning system to be easily scaled. To accommodate changes in substrate size the substrate supports and wafer handlers may be adjustable. Thus, few alterations are required for change-over between cleaning substrates of differing size.
Other inventive aspects of the cleaning system comprise, in one aspect the use of a megasonic tank cleaner, followed by a scrubber, and in another aspect the design of a cleaning system which does not employ a scrubber.
Further features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.